Okay, now that I have fixed my oil leaks, I have a vacuum leak... it is causing the idle to fluctuate when first started. It also causes my 4wd light to come on when I am off the gas. Now I am not new at mechanical type work, but when it comes to vacuum related, I get the basics, but diagnosing is a different ball game

 

Well, the diagnosis will all be in the location of the vacuum leak. First check all vacuum lines and connections for obvious disconnections/damage.
Then a method used for finding vacuum leaks, is using short sprays of throttle body cleaner in the engine bay with engine idle. Mainly around intake/throttle body. Change in idle will indicate the location of the leak.
CCKen, I know, advices to use propane for this (I'd say...fireworks!), so he might chime is as well

 

Listen to this advice.

Can you hear a vacuum leak or is the idle fluxuation what you consider the result of a vacuum leak?

I presume this XJ is an early version of real XJ's when you mention that the 4wd light comes on when you are off the gas.

 

When under heavy acceleration in at around maybe 3500 rpms I can hear a whistling sound and my 4wd light goes away the money
Minute the engine goes under any kind of load. It is an 87 4.0 xj

 

Check this out: I stole it from CCKen!!!!